Stack frame for electrical connections and the  method to fabricate thereof

ABSTRACT

A method of forming a conductive pattern on a metallic frame for manufacturing a stack frame for electrical connections is disclosed. In one embodiment, a recess is formed in the metallic frame and a conductive element is bonded in the recess to make a stack frame for electrical connections. In another embodiment, the process can be performed on both top surface and bottom surface of metallic frame to make another stack frame for electrical connections. In yet another embodiment, a package structure and a manufacturing method of forming a conductive pattern on a lead frame for electrical connections are disclosed.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to a packaging structure, and inparticularly, to a metallic frame for packaging and making electricalconnections.

II. Description of the Prior Art

Lead frame is a material for IC package and can be in variety of formssuch as QFP, TSOP, SOT or SOJ. The molded semiconductor devices areconstructed by assembling and interconnecting a semiconductor device toa lead frame. The structure is often molded with plastic material. Alead frame is made by a metal ribbon with a paddle (also known as a diepaddle, die-attach tab, or island) for attaching a semiconductor devicethereto and a plurality of leads arranged in a manner such that theleads do not overlap the paddle on which the semiconductor device is tobe mounted.

Conventionally, lead frame is used for die bond of an IC chip. Theprocess flow includes many stages which are wire bond, molding of ICchip, and the tests after trimming or forming. Various products can bemade by integrating or packaging the lead frame with other devices suchas inductors or capacitors. It's one of the main packaging processes inthe industry due to its easiness, maturity and better reliability.However, such kind of conventional process has many disadvantagesincluding: a. higher cost and more development works of molding devices;b. poor capability in area design which is only in the form of plane sothat product size doesn't shrink; and c. lacking of modular capabilityas it is only good for packaging a single device.

Accordingly, the present invention proposes a stack frame and itsmanufacturing method to overcome the above-mentioned disadvantages.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a method of forminga stack frame for manufacturing a structure for electrical connections.By removing one or more portions of the metallic substrate, a metallicframe having a plurality of pins is formed. The conductive pattern isformed on the metallic frame to make a plurality of electricalconnections to connect with a plurality of pins. Because metallic frameis metallic, it has better performance in heat dissipation andelectrical conductance.

Another objective of the present invention is to provide a method offorming a lead frame for manufacturing a package structure forelectrical connections. The conductive pattern is formed on the leadframe to make the electrical connections to the plurality of pins.Because the lead frame is metallic, it has better performance in heatdissipation and electrical conductance.

One embodiment in the present invention is to form a recess is in themetallic frame and at least one conductive element is bonded in therecess. I/O terminals of a conductive element can be electricallyconnected to a conductive layer by conventional technology, such as wirebond, gold-ball bond, conductive wires (by film process, printingprocess, electroplating) or a combination thereof.

The structure can be used in IC package in which a first conductiveelement is encapsulated mainly in the metallic frame, not molded withplastic material; and a second conductive element can be mounted on themetallic frame by SMT. The first conductive element and the secondconductive element can be active elements, such as IC chip, MOSFET, IGBTor diode, or passive elements, such as resistors, capacitors orinductors. The first conductive element and the second conductiveelement are directly electrically connected to the metallic frame (orpin), so it doesn't need additional PCB in order to connect them.Moreover, dispensing or gluing are used to replace molding encapsulationfor protection of the first conductive element. Therefore, it does notneed additional development of molding devices; it can save time andcost; and it's easier for design. Compared with lead frame and moldingin conventional structure of IC package, the structure can make theshortest electrical path for connecting the components so that it canreduce total impedance and increase electrical efficiency.

Another embodiment of the present invention is to use both top andbottom surfaces of metallic frame to make another structure forelectrical connections.

The present invention also discloses forming a filling layer to fill aleast one vacancy of the metallic frame. The filling layer can be apolymer material layer which can not only fill vacancies of the metallicframe but also cover the metallic frame. Accordingly, the polymermaterial layer can also be patterned on the stack frame so that theconductive layer can be contacted with the polymer material layer. As aresult, it can reduce the overall process cost.

The detailed technology and above preferred embodiments implemented forthe present invention are described in the following paragraphsaccompanying the appended drawings for people skilled in this field towell appreciate the features of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the accompanying advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed descriptionwhen taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a process flow of a method for manufacturing a structure forelectrical connection.

FIG. 2A and FIG. 2B illustrate a top view of stack frame with no vacancyand a top view of stack frame with at least one vacancy respectively.

FIG. 2C and FIG. 2D illustrate a schematic cross-sectional view of stackframe with no vacancy and a schematic cross-sectional view of stackframe with at least one vacancy respectively.

FIG. 3A illustrates a schematic cross-sectional view of the structure ofstack frame with no vacancy for electrical connections.

FIG. 3B illustrates a schematic cross-sectional view of the structure ofstack frame with no vacancy and with a recess in which a conductiveelement is bonded for electrical connections.

FIG. 3C illustrates a schematic cross-sectional view of the structure ofstack frame with no vacancy for electrical connections by process bothon the top surface and the bottom surface of the structure.

FIG. 3D illustrates a product structure with at least one firstconductive element on the structure in FIG. 3A.

FIG. 4A illustrates a schematic cross-sectional view of the structure ofstack frame with at least one vacancy for electrical connections.

FIG. 4B illustrates a schematic cross-sectional view of the structure ofstack frame with at least one vacancy and with a recess in which aconductive element is bonded for electrical connections.

FIG. 4C illustrates a schematic cross-sectional view of the structure ofstack frame with at least one vacancy for electrical connections byprocess on both the top surface and the bottom surface of the structure.

FIG. 4D illustrates another schematic cross-sectional view of thestructure of stack frame with at least one vacancy for electricalconnections.

FIG. 4E illustrates a product structure with at least one firstconductive element on the structure in FIG. 4A.

FIG. 5A illustrates a sectional view of the package structure of theembodiment of the present invention.

FIG. 5B to FIG. 5J illustrates a process flow for manufacturing apackage structure of the present invention.

FIG. 5K illustrates the top view of the package structure in FIG. 5A.

FIG. 5L illustrates the bottom view of the package structure in FIG. 5A.

DETAILED DESCRIPTION OF THE INVENTION

The detailed explanation of the present invention is described asfollowing. The described preferred embodiments are presented forpurposes of illustrations and description, and they are not intended tolimit the scope of the present invention.

The invention discloses a method for manufacturing a stack frame. Astack frame means a frame on which something is constructed to combinesome more functionality.

Please refer to FIG. 1, a method for manufacturing a stack frame isachieved by the following steps:

In step 11, a metallic substrate is provided.In step 12, a metallic frame having a plurality of pins is formed byremoving one or more portions of the metallic substrate.In step 13, a conductive pattern is formed on the metallic frame to makea plurality of electrical connections to connect with the plurality ofpins.

In step 11, the metallic substrate can be made of any conductivematerial, such as metallic material which includes and is not limited,Cu, Ag, Sn or a combination thereof. In step 12, the technology forremoving one or more portions of the metallic substrate to form ametallic frame having a plurality of pins can be any known method. Ametallic frame has a plurality of pins as I/O terminals, and pads areplaced underlying pins for external electrical connection. The metallicframe can be a lead frame or any other equivalent structure. In oneembodiment, the metallic frame can have no vacancy or at least onevacancy. Appearance or shape of the metallic frame depends on layout ofpads via which the pin of the metallic frame is electrically connectedto PCB or another conductive element, such as IC chip, MOSFET, IGBT,diode, resistor, choke or capacitor. In step 13, a conductive pattern isformed on the metallic frame by known techniques, such as film process,printing process, laser drilling or a combination thereof. Theconductive pattern comprises a plurality of electrical connections toconnect with the plurality of the plurality of pins. In one embodiment,at least one conductive layer is patterned on the metallic frame to makebetter performance of the electrical connections to the plurality ofpins.

FIG. 2A and FIG. 2B illustrate a top view of metallic frame 31 with novacancy and a top view of metallic frame 32 with at least one vacancy 33respectively. Metallic frame having a plurality of pins 34 can be in anysuitable appearance or shape for subsequent processing. FIG. 2C and FIG.2D illustrate a schematic cross-sectional view of a metallic frame 31with no vacancy and a schematic cross-sectional view of a metallic frame32 with a vacancy 33 respectively. In reference to both FIG. 2A and FIG.2C together, sections A-A′ in FIG. 2C are taken along line A-A′ shown inFIG. 2A. In reference to both FIG. 2B and FIG. 2D together, sectionsB-B′ in FIG. 2D are taken along line B-B′ shown in FIG. 2B. Thepreferred structures and manufacturing method are described in thefollowing embodiments.

First Embodiment

FIG. 3A illustrates a schematic cross-sectional view of a structure 100of stack frame with no vacancy for electrical connections. In oneembodiment, the structure 100 includes a metallic frame 101 with novacancy, a dielectric layer 102 and a conductive layer 103. Thedielectric layer 102 is disposed on the metallic frame 101. Theconducted layer 103 is formed on the dielectric layer 102 and filledinto vias which are formed inside of the dielectric layer 102. Thestructure 100 can include any other equivalent structure for electricalconnections as well; and the structure can be made of any suitablematerial by any suitable process. In another embodiment, as illustratedin FIG. 3B, a recess 118 is formed in the metallic frame 101 and aconductive element 111 (e.g., IC chip, MOSFET, IGBT, diode, resistor,choke or capacitor) is bonded in the recess 118 by conventionaltechniques (e.g., Ag gluing 119). There are many different ways tolocate the recess, for example, in one embodiment the recess is formedinside of the metallic frame; in another embodiment the recess is formedwith one side aligned with one edge of the metallic frame; and in yetanother embodiment the recess is formed with two sides aligned with twoedges of the metallic frame respectively. In one embodiment, the recesscan be formed in the metallic frame which comprises a plurality of submetallic frames, wherein a plurality of sub metallic frames are joinedtogether. In one embodiment, at least one conductive element is bondedin the recess. I/O terminals of the conductive element 111 can beelectrically connected to the conductive layer 103 by conventionaltechnology, such as wire bond, gold-ball bond, conductive wires (by filmprocess, printing process or electroplating) or a combination thereof.In one embodiment, the top surface 112 of the conductive element and thetop surface 113 of metallic frame are at the same horizontal level. Inyet another embodiment, as illustrated in FIG. 3C, the process can beperformed on both top surface 113 and bottom surface 114 of metallicframe. The features described above can also be applied to the structurein FIG. 3C.

FIG. 3D illustrates a product structure 150 with a first conductiveelement 105 on the structure 150 in FIG. 3A. A first pad 104 can beformed on the conductive layer 103 so that a conductive element 105(e.g., IC chip, MOSFET, IGBT, diode, resistor, choke or capacitor) canbe placed on the first pad 104. A second pad 106 can be formedunderlying the pins of the stack frame. The second pad 106 can be madeof any conductive material, such as Sn, Ni/Au or the like. The structure150 can be mounted on PCB or electrically connected to anotherconductive element (not shown) (e.g., IC chip, MOSFET, IGBT, diode,resistor, choke or capacitor) so that the conductive element 105 can beelectrically connected to PCB or another conductive element (not shown)via the conductive path including the first pad 104, the conductivelayer 103, metallic frame (or pin) 101 and a second pad 106. It shouldbe noted that the way to make electrical connections varies withdifferent kinds of products and process performed on the metallic frame.It can include many ways and is not limited to the ways described above.It can be readily appreciated by those skilled in the art and thus willnot be further described herein.

Second Embodiment

FIG. 4A illustrates a schematic cross-sectional view of the structure200 of stack frame with at least one vacancy 221 for electricalconnections. In one embodiment, the structure includes a metallic frame201 with at least one vacancy 221, a dielectric layer 202 and aconductive layer 203. The filling layer 222 is filled with a least onevacancy 221 of the metallic frame. The dielectric layer 202 is disposedon the metallic frame 201 and the conducted layer 203 is formed on thedielectric layer 202 and filled into vias which are formed inside of thedielectric layer 202. The structure 200 can include any other equivalentstructure for electrical connections. The structure can be made of anysuitable material and can be made by any suitable process. In anotherembodiment, as illustrated in FIG. 4B, a recess 218 is formed in themetallic frame 201 and at least one conductive element 211 (e.g., ICchip, MOSFET, IGBT, diode, resistor, choke or capacitor) is bonded inthe recess 218 by conventional techniques (e.g., Ag gluing 219). Thereare many different ways to locate the recess, for example, in oneembodiment the recess is formed inside of the metallic frame; in anotherembodiment the recess is formed with one side aligned with one edge ofthe metallic frame; and in yet another embodiment the recess is formedwith two sides aligned with two edges of the metallic framerespectively. In one embodiment, the recess can be formed in themetallic frame which comprises a plurality of sub metallic frames,wherein a plurality of sub metallic frames are joined together. In oneembodiment, at least one conductive element is bonded in the recess. I/Oterminals of the conductive element 211 can be electrically connected tothe conductive layer by conventional technology, such as wire bond,gold-ball bond, conductive wires (by film process, printing process orelectroplating) or a combination thereof. In one embodiment, the topsurface 212 of the conductive element and the top surface 213 ofmetallic frame are at the same horizontal level. In yet anotherembodiment, as illustrated in FIG. 4C, the process can be performed ontop surface 213 and bottom surface 214 of metallic frame.

Please refer back to FIG. 3A, there is a structural difference betweenFIG. 3A and FIG. 4A. The metallic frame of the structure 100 in FIG. 3Ahas no vacancy; whereas the metallic frame of the structure 200 in FIG.4A has at least one vacancy 221 which can be filled by the filling layer222. In one embodiment, the filling layer can fill at least one vacancy202 of the metallic frame 201 and cover the metallic frame 201. Thefilling layer 222 includes any suitable material, such as a polymermaterial or the like. The polymer material includes a photoresist. Inone embodiment, underlying the metallic frame is a supporting layer (notshown), such as polyimide film (PI film), which can support the fillinglayer 222. At the end of the overall process, the supporting layer canbe removed. In one embodiment, supporting layer is not necessary. In oneembodiment, please refer to FIG. 4D, the filling layer and thedielectric layer can be a single layer 223. In one preferred embodiment,the single layer 223 is a polymer material layer (e.g., phtotoresist ornegative photoresist). The polymer material layer not only can fill thevacancies but also can be patterned on the metallic frame by some knowntechniques, such as lithography process, laser drilling or the like, sothat the conductive layer 203 can be contacted with the polymer materiallayer. Accordingly, the overall processing cost can be reduced.Furthermore, the features described above in FIG. 4B and FIG. 4D canalso be applied to the structure in FIG. 4C as well.

FIG. 4E illustrates another product structure 250 with a firstconductive element 205 on the structure 200 in FIG. 4A. A first pad 204is formed on the conductive layer 203 so that a conductive element 205(e.g., IC chip, MOSFET, IGBT, diode, resistor, choke or capacitor) canbe placed on the first pad 204. A second pad 206 can be formedunderlying the pins of the stack frame. The second pad 206 can be madeof any conductive material, such as Sn, Ni/Au or the like. The structure250 can be mounted on PCB or electrically connected to anotherconductive element (not shown) (e.g., IC chip, MOSFET, IGBT, diode,resistor, choke or capacitor) so that the first conductive element 205can be electrically connected to a PCB or another conductive element(not shown) via the conductive path including the first pad 204, theconductive layer 203, metallic frame (or pin) 201 and a second pad 206.It should be noted that the way to make electrical connections varieswith different kinds of products and process performed on the metallicframe. It can include many ways and is not limited to the ways discussedabove. It can be readily appreciated by those skilled in the art andthus will not be further described herein.

The following embodiment discloses a package structure and itsmanufacturing method. In the embodiment, the metallic frame is a leadframe and the lead frame is the main constituent of the packagestructure.

Third Embodiment

FIG. 5A illustrates a sectional view of the package structure 300. Thepackage structure 300 includes a lead frame 301, a filling layer 306, afirst conductive element 304, a conductive pattern 312, a protectivelayer 311, a conductive pad 313, and at least one second conductiveelement 314. A lead frame has a plurality of pins 315 which can be inmany forms, such as I/O terminals or pads (not shown) which are placedunderlying pins 315 for external electrical connection. The appearanceor shape of the lead frame depends on the layout of the pads via whichthe structure 300 is electrically connected to PCB or a third conductiveelement (not shown), such as IC chip, MOSFET, IGBT, diode, resistor,choke or capacitor. In one embodiment, the lead frame 301 can have novacancy or at least one vacancy. The structure 300 can include any otherequivalent structure for a package structure, and it can be made of anysuitable material and manufactured by any suitable process. A lead frame301 can be made of conductive material, such as Ag, Cu, Sn or acombination thereof. A conductive pattern 312 is formed on the leadframe 301 by some known techniques, such as film process, printingprocess, laser drilling or a combination thereof. In one embodiment, atleast one conductive layer is patterned on the lead frame 301 to makebetter performance of a plurality of electrical connections to the pins315.

One aspect of structural difference between lead frames lies in whetherit has vacancy or not. Besides that, the remaining of the structure oflead frame are almost the same. The preferred structures andmanufacturing method in the following description refer to performingthe film process on the lead frame which has at least one vacancy.

FIG. 5B to FIG. 5H illustrate a sectional view of process flow formanufacturing the package structure 300.

As illustrated in FIG. 5B, a recess 303 is formed in the lead frame 301with at least one vacancy 302. The recess 303 can be formed by a knowntechnology, such as etching or surface coarsening. There are manydifferent ways to locate the recess, for example, in one embodiment therecess is formed inside of the lead frame; in another embodiment therecess is formed with one side aligned with one edge of the lead frame;and in yet another embodiment the recess is formed with two sidesaligned with two edges of the lead frame respectively. In oneembodiment, the recess can be formed in the lead frame which comprises aplurality of sub lead frames, wherein a plurality of sub lead frames arejoined together.

Next, as illustrated in FIG. 5C, a first conductive element 304, such asIC chip, MOSFET, IGBT or diode, is bonded in the recess 303 byconventional techniques (e.g., Ag gluing 305). In one embodiment, atleast one first conductive element is bonded in the recess.

Next, as illustrated in FIG. 5D, the filling layer 306 is filled into atleast one vacancy 302 of the lead frame 301. In one embodiment, thefilling layer can fill at least one vacancy 302 of the lead frame 301and cover the lead frame 301. A supporting layer, such as polyimide film(PI film), is attached underlying the lead frame 301 to support thefilling layer 306. At the end of the overall process, the supportinglayer can be removed. In one embodiment, supporting layer is notnecessary. The filling layer 306 includes any suitable material, such asa polymer material or the like. The polymer material can be aphotoresist. In the preferred embodiment, the filling layer 306 is apolymer material layer (e.g., phtotoresist or negative photoresist). Thepolymer material layer not only can fill a plurality of vacancies butalso can be patterned on the lead frame 301 by known techniques, such aslithography process, laser drilling, so that the conductive pattern 312can be contacted with the polymer material layer.

Please refer to FIG. 5E, a polymer material (e.g., phtotoresist ornegative photoresist) layer 306 is patterned to expose the I/O terminalsof the first conductive element 304 by a known process, such aslithography process, laser drilling or the like. A conductive pattern312, which will be discussed in next stage, is formed on the lead frame.

Next, as illustrated in FIG. 5F and FIG. 5I, a thin copper layer 308 issputtered over the polymer material layer 306, a portion of pins of thelead frame 315 and I/O terminals of the first conductive element 304. Athin copper layer 108 and a thick copper layer 310 (shown in FIG. 5I)are combined into a conductive pattern 312 to make two groups ofelectrical connections. The first group of electrical connections isbetween a portion of pins of lead frame 315 and I/O terminals of thefirst conductive element 304. The second group of electrical connectionsis between the second conductive element 314 and I/O terminals of thefirst conductive element 304. A thin copper layer 308 is used to contactI/O terminals of the first conductive element 304 to reduce the contactresistance between I/O terminals of the first conductive element 304 andthe conductive pattern 312.

Please continuously refers to FIG. 5F and FIG. 5I. A photoresist layer309 (e.g., positive photoresist) is patterned on a portion of thincopper layer 108 to expose the remaining portion of thin copper layer308. Then a thick copper layer 310 is formed on the remaining portion ofthin copper layer 308 by a known process, such as electroplating. As aresult, a thin copper layer 308 and a thick copper layer 310 (shown inFIG. 5I) are combined into a conductive pattern 312 to make two groupsof electrical connections described above.

In one embodiment, I/O terminals of the first conductive element 304 canbe electrically connected to the conductive pattern 312 by conventionaltechnology, such as wire bond, gold-ball bond, conductive wires (by filmprocess, printing process, or electroplating) or a combination thereof.FIG. 5H and FIG. 5G illustrate electrical connections between the I/Oterminal of the first conductive element 304 and the conductive pattern312 by way of wire bonds 316 or gold ball bonds 317. A gold-ball bond isused to contact I/O terminals of the first conductive element 304 toreduce contact resistance between I/O terminals of the first conductiveelement 304 and the conductive pattern 312.

Next, as illustrated in FIG. 5J and FIG. 5A, the photoresist layer 309is removed. In one embodiment, the thick copper layer 310 can be trimmedto a suitable thickness. Then, a protective layer 311 is selectivelypatterned to expose a portion of the conductive pattern 312. A first pad313 can be formed on the portion of the conductive pattern 312 by aknown process, such as printing solder, to connect with a secondconductive element 314, such as choke, capacitor or resistor. Then asecond pad 318 can be formed underlying the lead frame to furtherconnect to PCB. The second pad 318 can be made of any conductivematerial, such as Sn, Ni/Au or the like. FIG. 5A illustrates a productstructure 300 of the embodiment of the present invention.

FIG. 5K and FIG. 5L illustrate the top view and bottom view of theproduct structure 300 in FIG. 5A. In reference to both FIG. 5A and FIG.5K together, sections C-C′ in FIG. 5A are taken along line C-C′ shown inFIG. 5K. In reference to both FIG. 5A and FIG. 5L together, sectionsC-C′ in FIG. 5A are taken along line C-C′ shown in FIG. 5L. Asillustrated in FIG. 5K, the top view of the product structure 300 mainlyincludes a lead frame 301 and a second conductive element 314 in FIG.5A. As illustrated in FIG. 5L, the bottom view of the product structure300 mainly includes a lead frame 301 and a second pad 318 in FIG. 5A.The first conductive element (not shown) 304 is embedded in the productstructure 300. It should be noted that the way to make electricalconnections varies with different kinds of products and processperformed on the metallic frame. It can include many ways and is notlimited to the ways discussed above. It can be readily appreciated bythose skilled in the art and thus will not be further described herein.

It follows from description of the above embodiments that the structurein the present invention and the method for manufacturing the same canoffer many advantages including: 1. Better performance of heatdissipation and electrical conductance as the metallic frame ismetallic. 2. Smaller size by forming a recess in the metallic frame andusing conventional technology and process, such as film process,printing process or electroplating, to connect all the conductiveelements by a conductive pattern with the metallic frame. 3. Versatileapplications including active devices such as IC chip, MOSFET, IGBT ordiode, or passive devices such as resistors, capacitors or inductors.

The above disclosure is related to the detailed technical contents andinventive features thereof. People skilled in this field may proceedwith a variety of modifications and replacements based on thedisclosures and suggestions of the invention as described withoutdeparting from the characteristics thereof. Nevertheless, although suchmodifications and replacements are not fully disclosed in the abovedescriptions, they have substantially been covered in the followingclaims as appended.

1. A method for manufacturing a stack frame for electrical connections,the method comprising the steps of: a. providing a metallic substrate;b. forming a metallic frame having a plurality of pins by removing oneor more portions of the metallic substrate; and c. forming a conductivepattern on the metallic frame, wherein the conductive pattern comprisesa plurality of first electrical connections to connect with theplurality of pins.
 2. The method according to claim 1, wherein forming aconductive pattern is performed by at least one of film process,printing process or laser drilling.
 3. The method according to claim 1,wherein the metallic frame has at least one vacancy, further comprisingthe step of: forming a filling layer to fill said at least one vacancy.4. The method according to claim 3, further comprising the step of:forming a supporting layer underlying the metallic frame to support thefilling layer.
 5. The method according to claim 4, wherein the fillinglayer comprises a polymer material.
 6. The method according to claim 1,further comprising the steps of: forming a recess in the metallic frame;and placing a first conductive element having at least one first I/Oterminal in the recess, wherein the conductive pattern further comprisesa plurality of second electrical connections to connect with said atleast one first I/O terminal of the first conductive element.
 7. Themethod according to claim 6, further comprising the step of: placing asecond conductive element having a least one second I/O terminal on themetallic frame, wherein the conductive pattern further comprises aplurality of third electrical connections to connect with said a leastone second I/O terminal of the second conductive element.
 8. The methodaccording to claim 1, further comprising the step of: placing a firstconductive element having at least one first I/O terminal on themetallic frame, wherein the conductive pattern further comprises aplurality of second electrical connections to the first conductiveelement.
 9. The method according to claim 3, wherein the filling layeris made of a polymer material, further comprising the step of:patterning the filling layer on the metallic frame.
 10. The methodaccording to claim 5, wherein a polymer material is a photoresist. 11.The method according to claim 1, wherein the metallic substrate is madeof at least one of Cu, Ag or Sn.
 12. The method according to claim 6,wherein the first conductive element comprises at least one of IC chip,MOSFET, IGBT, diode, choke, capacitor or resistor.
 13. The methodaccording to claim 1, wherein the conductive pattern further comprisesat least one of wire bond or gold-ball bond.
 14. A method formanufacturing a stack frame for electrical connections, the methodcomprising the steps of: a. providing a metallic substrate; b. forming ametallic frame having a plurality of pins by removing one or moreportions of the metallic substrate, wherein the stack frame has a firstsurface and a second surface; c. forming a first conductive pattern onthe first surface of the stack frame, wherein the first conductivepattern comprises a plurality of first electrical connections to connectwith the plurality of the pins; and d. forming a second conductivepattern on the second surface of the stack frame, wherein the secondconductive pattern comprises a plurality of second electricalconnections to connect with the plurality of the pins.
 15. The methodaccording to claim 14, wherein forming a first conductive pattern andforming a second conductive pattern is performed by at least one of filmprocess, printing process or laser drilling.
 16. The method according toclaim 14, wherein the metallic frame has at least one vacancy, furthercomprising the step of: forming a filling layer to fill said at leastone vacancy.
 17. The method according to claim 15, wherein the fillinglayer comprises a polymer material.
 18. The method according to claim14, further comprising the steps of: forming a recess in the metallicframe; and placing a first conductive element having at least one firstI/O terminal in the recess, wherein the conductive pattern furthercomprises a plurality of third electrical connections to connect withsaid at least one first I/O terminal of the first conductive element.19. The method according to claim 14, further comprising the steps of:forming a first pad on first conductive pattern; and forming a secondpad on second conductive pattern.
 20. A method for manufacturing apackage structure, the method comprising the steps of: a. providing alead frame having a plurality of pins; b. forming a recess in the leadframe; c. placing a first conductive element having at least one firstI/O terminal in the recess; and d. forming a conductive pattern on thelead frame, wherein the conductive pattern comprises a plurality ofelectrical connections to connect with the plurality of pins and said atleast one first I/O terminal of the first conductive element.
 21. Themethod according to claim 20, further comprising the steps of: forming afirst pad on the conductive pattern; and attaching a second conductiveelement having at least one second I/O terminal to the lead frame byjoining the first pad with said at least one second I/O terminal of thesecond conductive element.
 22. The method according to claim 20, whereinthe lead frame has at least one vacancy and forming a conductive patternin the step d comprises the steps of: forming a polymer material layerto fill said at least one vacancy of the lead frame; and patterning thepolymer material layer to expose said at least one first I/O terminal ofthe first conductive element.
 23. The method according to claim 22,wherein forming a conductive pattern in the step d further comprises thestep of: attaching a supporting layer underlying the lead frame tosupport the polymer material photoresist layer.
 24. The method accordingto claim 22, wherein forming a conductive pattern in the step d furthercomprises the steps of: forming a first conductive layer over thepolymer material layer; and forming the conductive pattern on the firstconductive layer.
 25. The method according to claim 23, wherein thesupporting layer comprises a polyimide film.
 26. The method according toclaim 22, wherein the polymer material layer comprises a negativephotoresist.
 27. The method according to claim 23, further comprisingthe steps of: removing the supporting layer; and forming a second padunderlying the lead frame.
 28. The method according to claim 20, whereinthe first conductive element comprises at least one of IC chip, MOSFET,IGBT, diode, choke, capacitor or resistor.
 29. The method according toclaim 21, wherein the second conductive element comprises at least oneof IC chip, MOSFET, IGBT, diode, choke, capacitor or resistor.
 30. Themethod according to claim 20, wherein the conductive pattern comprises ametallic material.
 31. The method according to claim 30, wherein themetallic material comprises at least one of Cu, Ag or Sn.
 32. A packagestructure, comprising: a lead frame having a plurality of pins; a recessin the lead frame; a first conductive element having at least one firstI/O terminal in the recess; and a conductive pattern on the lead frame,wherein the conductive pattern comprises a plurality of electricalconnections to connect with the plurality of pins and said at least onefirst I/O terminal of the first conductive element.
 33. The packagestructure according to claim 32, further comprising a second conductiveelement having at least one second I/O terminal, wherein the conductivepattern further comprises a first pad to join said at least one secondI/O terminal of the second conductive element.
 34. The package structureaccording to claim 32, further comprising a second pad underlying thelead frame so as to connect with a PCB.
 35. The package structureaccording to claim 32, wherein the lead frame has at least one vacancy,further comprising a filling layer which is filled into said at leastone vacancy of the lead frame.
 36. The package structure according toclaim 35, wherein the filling layer comprises a polymer material. 37.The package structure according to claim 36, wherein the polymermaterial comprises a negative photoresist.
 38. The package structureaccording to claim 32, wherein the first conductive element comprises atleast one of IC chip, MOSFET, IGBT, diode, choke, capacitor or resistor.39. The package structure according to claim 33, wherein the secondconductive element comprises at least one of IC chip, MOSFET, IGBT,diode, choke, capacitor or resistor.
 40. The method according to claim32, wherein the conductive pattern further comprises at least one ofwire bond or gold-ball bond.
 41. The method according to claim 6,wherein the metallic frame comprises a plurality of sub metallic frames.42. The method according to claim 18, wherein the metallic framecomprises a plurality of sub metallic frames.
 43. The method accordingto claim 20, wherein the lead frame comprises a plurality of sub leadframes.
 44. The package structure according to claim 32, wherein thelead frame comprises a plurality of sub lead frames.